Repair Mac External Hard Drive without Disk Utility

Can you afford to lose valuable files stored on your Mac external hard drive? For sure, no. But, at times, there may arise a situation wherein an unexpected event corrupts the partition table, EFI partition, or APFS/HFS file system of the Mac external storage drive. This logical damage of the external drive makes data or the drive inaccessible on Mac.

In this blog, we’ll share various methods to repair Mac external hard drive without Disk Utility.

We aren’t suggesting you skip Disk Utility repair mechanism, however, we are offering a few advanced solutions.

We’ll also present the software-based method to recover data from a corrupt external drive on Mac. But before that, it is crucial to know the storage drive’s file system and how it may get corrupt.

Mac File System and Its Importance

Your Mac external hard drive contains reserved space for GUID Partition Table, EFI System Partition, and APFS Container. The APFS container comprises Container superblock, Checkpoint area, Space manager area, and storage for objects and file data. The container can have multiple volumes which are also known as file systems.

The Mac’s file system allows storage and retrieval of data on
the storage drive.

Reasons for File System Corruption

The following situations
may damage the storage drive’s file system, which may not get fixed with Disk Utility’s First Aid feature:

An application may inadvertently write into the file system thereby
causing corruption on the disk.

If the block containing the file system of the drive turns
bad, then the storage drive fails.

Though likely, a malware residing on the Mac system corrupts
the file system and restricts any access to the drive. It’ll perform write
operations on the space intended for the file system.

Few reasons for corruption of legacy file-system formatted storage drive are as follows:

A macOS crash or abrupt power cut results in non-syncing of information to the file system, which results in its corruption.

The sudden removal of an external storage drive without proper un-mounting may result in an incomplete write operation and corruption.

If the external storage drive does not un-mount due to running programs that are accessing the drive, forced ejection can corrupt its file system.

Methods to Repair Mac Storage Drive without Disk Utility

Method 1: By Using Safe Mode

The Disk Utility’s First
Aid command may not be able to fix the issue of file system corruption for the startup
disk. In such a case, use Safe Mode
to repair your startup drive. The steps are as follows:

Turn on your Mac and press-hold Shift key when you hear the startup chime and release the key once you see the login window.

Your Mac performs all the troubleshooting checks on the startup disk and boots into Safe Mode.

Restart your Mac without pressing any key to boot usually.

Method 2: By Using FSCK Command in Single-User Mode

If Safe Mode can’t repair
the corrupt file system of Mac storage drive, you can try running file system consistency
check (fsck) command in Single-User Mode. Steps are as follows:

Make sure you know the identifier of the external hard drive
before running fsck command on it. In case you are unaware on how to determine
the external hard drive identifier then connect your external drive to Mac and
launch the Terminal.app. In the Terminal window, enter the command diskutillist < press Return. Check
the name of the volume under IDENTIFIER.
For instance, the identifier could be disk4s1. Now navigate through the steps
to use fsck for repairing Mac external hard drive.

Turn on your Mac and press-hold Command + S keys and release the keys once you see white text to boot your Mac in single-user mode.

On the prompt, type fsck_hfs –f /dev/disk4s1 and hit Return.

When you receive the message “File system was modified, re-run the above fsck command.

Use the fsck command multiple times until you receive the message, “The volume appears to be OK.”

Reboot your Mac and this time don’t press any key to boot your Mac normally.

Method 3: By Using FSCK Command from Terminal

If Disk Utility’s First
Aid command can’t fix the file system corruption issue on the non-startup drive
or external storage drive, run fsck command in the macOS Terminal. Steps are as
follows:

Type sudo fsck_apfs -y /dev/external_storage_id and hit Return. [The fsck_apfs verifies and repairs apfs containers and volumes. If the external storage drive is in the hfs format, you can use fsck_hfs instead of fsck_apfs. The parameter -y repairs any damage that is found.]

Enter your system password when prompted.

Check the message provided by the fsck command.

Type unmount /dev/external_storage_id and hit Return.

Use the fsck command again until it says, “The volume appears to be OK.”

This Mac data recovery software
helps you recover the inaccessible data from a storage drive whose file system,
EFI partition, or partition table is lost, deleted, or damaged. In other words,
if all the above methods fail to repair the drive then perform safe data
recovery with an advanced disk recovery tool.

Steps to recover data from
the corrupt Mac external drive are:

Free download the *trial version of Stellar Data Recovery Premium for Mac

Install the Stellar software on your Mac in the Applications folder.

Launch the software. Toggle on the file types to customize the scan. Click Next.

*Trial software allows you to scan and preview files. You need to activate the software to save recoverable files and unlock all its features.

Once the data is recovered, you can erase the external hard drive to recreate a new file system by using Disk Utility. Restore the recovered data to the newly formatted external hard drive.

Precautions and Best Practices

The following precautions
and best practices will lessen the chances of file system corruption:

Back up your data periodically

Always unmount your external hard drive safely.

Do not eject or pull the cable of the drive abruptly.

Don’t let your Mac shut down suddenly while the external drive is in process of file transfer or indulge in disk management tasks.

Conclusion

A file system corruption is
a serious issue and may lead to complete damage of your Mac external storage
drive, making data inaccessible. We hope the blog has provided sufficient information
to help mitigate file system corruption.

For corrupt drive, you
need to run your Mac in Safe Mode to repair file system issues—this works
similar to Disk Utility’s First Aid on the startup drive. Or else, use the
“file system consistency check” fsck command in Single-User Mode. You may run the
fsck command from Terminal to fix the file system corruption issue.

The fsck troubleshooting method is risky and can result in data loss, so back up the drive before performing the steps. If you can’t back up the data or want a safer solution, use a Mac data recovery software such as Stellar Data Recovery Premium for Mac to scan and recover data from the corrupt drive. Subsequently, erase the external storage drive and restore data to the drive.

About The Author

I was working on my MacBook Pro OS X 10.10.5 with my external hard drive (Toshiba) plugged in. Unknowingly I ejected the hard drive without properly unmounting it. When I reconnected the hard drive and ran Disk Utility it told me to “Disk utility can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore you backed-up files.” I checked out Disk Warrior and its site says buy it at $99. I can’t pay this much amount at this time? Could you suggest me some other way to repair my external hard drive?

Tom Patrick March 23, 2016

Hi Max,

I recommend you download & register Stellar Volume Optimizer software to repair the corrupt external hard disk drive. This software will rebuild the damaged disk directory and bring back you hard drive to life.

Christopher Janke March 28, 2016

I have a movie in my Mac OS X El Capitan (in .mp4 format) and I am unable to move it to an external SSD. Is there any suitable way to do it?

Cyborg March 28, 2016

How do I proceed to repair Mac external hard drive with command lines?

Tom March 29, 2016

Launch terminal and type below code:

diskutil repairvolume /Volumes/DriveName/

Press Return

Minor fixes will be taken care of using the above command lines.

Hope this helps

Tom Patrick March 29, 2016

Your external drive is formatted as NTFS which is a PC format. But, OS X is developed to read a NTFS drive and copy the data to your Mac system, but it can’t write anything on NTFS. If the hard-drive is going to be used only in a Mac system, then it needs to be re-formatted in the Mac OS Journaled format. This is very simple and you can do it from here: http://support.apple.com/kb/HT3509